1. Field of the Invention
The apparatus of the present invention relates to combustion devices such as incineration furnaces and the like, and in particular, relates to a combustion-gas cooling device which is mounted on the combustion device wherein dust form slag is generated. More particularly, the apparatus of the present invention relates to a combustion device that combusts or otherwise heats material at a high temperature so that ash components therein liquify, and in which fumes and fine particles of liquified ash entrained in the combustion gasses formed therein are converted to fly ash which is nonadhering to surfaces of the combustion-gas exhausting section.
2. Prior Art
Slag is a material composed of various noncombustible substances remaining after combustion takes place at a temperature greater than the melting point of the slag. Slag can usually exist in three general states: at low temperatures, slag is a nonadherent solid; at medium temperatures, slag is a highly viscous liquid which is relatively adhering and nonflowing; and at high temperatures, slag is a fluid of low viscosity which may or may not adhere, but which flows readily.
As an example of a prior art combustion apparatus, the combustion apparatus 10 shown in FIG. 6, is known in which a cyclone-type combustion furnace 20 contains a combustion chamber 22 for receiving particles which are to be combusted. After the particles are combusted, the remnants are carried by centrifugal force around the face of the inner wall, adhere to the inner wall, and are heated to liquefaction, resulting in combustion gas and slag. Therefore, unburned components are exhausted from exhaust port 26. The slag separation pathway 34 in the slag separation chamber 30 at the combustion gas inlet 33 mediates the supply, and the slag is removed by passing out through the exhaust port 26; the greater part of the slag flows down the inner wall of the combustion chamber, flows down the inner wall of the exhaust port 26 as combustion gas is exhausted from combustion gas chamber 22, and passes down slag separation pathway 34 in slag separation chamber 30 at combustion gas inlet 33 of slag separation chamber 30, while a smaller portion of the slag is carried out as particles or droplets suspended in the moving combustion gas.
Along the slag separation path 34 in slag separation chamber 30, combustion gas exhausted from combustion gas inlet 33 is separated from the slag. The combustion gas is then exhausted through exhaust port 35 and is then supplied to a treatment apparatus (for example heat recovery apparatus 50) for final exhaustion to the outside, while the thus separated slag is expelled to a treatment apparatus at slag outlet 36.
At the exhaust port 35, in order that the subsequent treatment apparatus is supplied with combustion gas of a temperature low enough not to damage the treatment apparatus, and in order that slag is converted into non-adhering fly ash, low temperature gas is supplied to be mixed with the combustion gas to produce a mixture of a suitably low temperature downstream of the mixing site, by low temperature gas supply pipe 35A; the high temperature of the combustion gas (for example 1300.degree.-1500.degree. C.) is reduced to below 1000.degree. C.
If the high temperature combustion gas in which slag is suspended is allowed to proceed past exhaust port 35, and if the slag suspended in the combustion gas subsequently encounters a low temperature surface, it is transformed to a highly viscous or solid state and will adhere to and accumulate on the surface, and accordingly, a great deal of labor will have to be expended to remove the accumulated slag.
Therefore, in combustion apparatus 10, suitably low temperature gas is supplied directly from the low temperature gas supply pipe 35A to the interior of exhaust port 35, however it is not possible to mix high temperature combustion gas and low temperature gas sufficiently rapidly and homogeneously, and it is not possible to avoid the production of an adhering ash fraction and the restriction of flow in the low temperature gas supply pipe 35A and combustion gas exhaust port 35 by the rapid accumulation of adhering slag downstream of the opening of the low temperature gas supply pipe 35A and exhaust port 35, which requires intermittent cessation of operation of the combustion apparatus, since the formation of the adhering slag necessitates removal. The invention is directed toward overcoming these problems.